Two-component complex tone pairs are synthesized so that complementary pairs have identical amplitude modulations, but frequency modulations that are in opposite directions. The discriminability of these complementary complex tone pairs is related to the difference in the envelope-weighted averages of their instantaneous frequency functions. When the complementary complex tone pairs are just discriminable we infer that the components have been spectrally resolved. The results indicate that discriminability remains good until the separation between the components reaches the estimated -3dB bandwidth of the traveling wave envelope observed by von Bekesy. Further experiments will study the difference in pitch of complementary complex tone pairs and the low (periodicity) pitch of multi-tone complexes.